The Honeywell Q651A 1009 3-Position Switch Subbase is a wall-mounted unit designed for use with Honeywell Q651A 1009 thermostats. It features a corded electric power source and operates on 24V low voltage. The switch control style allows for easy adjustment between heat, cool, and off settings. Made of plastic and measuring 2.16 inches in display size, this subbase is a reliable and durable accessory for HVAC and refrigeration systems. With its compatibility with specific Honeywell thermostat models and brand, this product ensures efficient system switching and programmability for various temperature control needs.